/* * Common bit i/o utils * Copyright (c) 2000, 2001 Fabrice Bellard * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at> * Copyright (c) 2010 Loren Merritt * * alternative bitstream reader & writer by Michael Niedermayer <michaelni@gmx.at> * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /** * @file * bitstream api. */ #include "libavutil/avassert.h"#include "libavutil/qsort.h"#include "avcodec.h"#include "internal.h"#include "mathops.h"#include "put_bits.h"#include "vlc.h" const uint8_t ff_log2_run[41]={ 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,}; void avpriv_align_put_bits(PutBitContext *s){    put_bits(s, s->bit_left & 7, 0);} void avpriv_put_string(PutBitContext *pb, const char *string,                       int terminate_string){    while (*string) {        put_bits(pb, 8, *string);        string++;    }    if (terminate_string)        put_bits(pb, 8, 0);} void avpriv_copy_bits(PutBitContext *pb, const uint8_t *src, int length){    int words = length >> 4;    int bits  = length & 15;    int i;     if (length == 0)        return;     av_assert0(length <= put_bits_left(pb));     if (CONFIG_SMALL || words < 16 || put_bits_count(pb) & 7) {        for (i = 0; i < words; i++)            put_bits(pb, 16, AV_RB16(src + 2 * i));    } else {        for (i = 0; put_bits_count(pb) & 31; i++)            put_bits(pb, 8, src[i]);        flush_put_bits(pb);        memcpy(put_bits_ptr(pb), src + i, 2 * words - i);        skip_put_bytes(pb, 2 * words - i);    }     put_bits(pb, bits, AV_RB16(src + 2 * words) >> (16 - bits));} /* VLC decoding */ #define GET_DATA(v, table, i, wrap, size)                   \{                                                           \    const uint8_t *ptr = (const uint8_t *)table + i * wrap; \    switch(size) {                                          \    case 1:                                                 \        v = *(const uint8_t *)ptr;                          \        break;                                              \    case 2:                                                 \        v = *(const uint16_t *)ptr;                         \        break;                                              \    case 4:                                                 \        v = *(const uint32_t *)ptr;                         \        break;                                              \    default:                                                \        av_assert1(0);                                      \    }                                                       \}  static int alloc_table(VLC *vlc, int size, int use_static){    int index = vlc->table_size;     vlc->table_size += size;    if (vlc->table_size > vlc->table_allocated) {        if (use_static)            abort(); // cannot do anything, init_vlc() is used with too little memory        vlc->table_allocated += (1 << vlc->bits);        vlc->table = av_realloc_f(vlc->table, vlc->table_allocated, sizeof(VLC_TYPE) * 2);        if (!vlc->table) {            vlc->table_allocated = 0;            vlc->table_size = 0;            return AVERROR(ENOMEM);        }        memset(vlc->table + vlc->table_allocated - (1 << vlc->bits), 0, sizeof(VLC_TYPE) * 2 << vlc->bits);    }    return index;} typedef struct VLCcode {    uint8_t bits;    uint16_t symbol;    /** codeword, with the first bit-to-be-read in the msb     * (even if intended for a little-endian bitstream reader) */    uint32_t code;} VLCcode; static int compare_vlcspec(const void *a, const void *b){    const VLCcode *sa = a, *sb = b;    return (sa->code >> 1) - (sb->code >> 1);}/** * Build VLC decoding tables suitable for use with get_vlc(). * * @param vlc            the context to be initialized * * @param table_nb_bits  max length of vlc codes to store directly in this table *                       (Longer codes are delegated to subtables.) * * @param nb_codes       number of elements in codes[] * * @param codes          descriptions of the vlc codes *                       These must be ordered such that codes going into the same subtable are contiguous. *                       Sorting by VLCcode.code is sufficient, though not necessary. */static int build_table(VLC *vlc, int table_nb_bits, int nb_codes,                       VLCcode *codes, int flags){    int table_size, table_index, index, code_prefix, symbol, subtable_bits;    int i, j, k, n, nb, inc;    uint32_t code;    volatile VLC_TYPE (* volatile table)[2]; // the double volatile is needed to prevent an internal compiler error in gcc 4.2     table_size = 1 << table_nb_bits;    if (table_nb_bits > 30)       return -1;    table_index = alloc_table(vlc, table_size, flags & INIT_VLC_USE_NEW_STATIC);    ff_dlog(NULL, "new table index=%d size=%d\n", table_index, table_size);    if (table_index < 0)        return table_index;    table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index];     /* first pass: map codes and compute auxiliary table sizes */    for (i = 0; i < nb_codes; i++) {        n      = codes[i].bits;        code   = codes[i].code;        symbol = codes[i].symbol;        ff_dlog(NULL, "i=%d n=%d code=0x%"PRIx32"\n", i, n, code);        if (n <= table_nb_bits) {            /* no need to add another table */            j = code >> (32 - table_nb_bits);            nb = 1 << (table_nb_bits - n);            inc = 1;            if (flags & INIT_VLC_LE) {                j = bitswap_32(code);                inc = 1 << n;            }            for (k = 0; k < nb; k++) {                int bits = table[j][1];                ff_dlog(NULL, "%4x: code=%d n=%d\n", j, i, n);                if (bits != 0 && bits != n) {                    av_log(NULL, AV_LOG_ERROR, "incorrect codes\n");                    return AVERROR_INVALIDDATA;                }                table[j][1] = n; //bits                table[j][0] = symbol;                j += inc;            }        } else {            /* fill auxiliary table recursively */            n -= table_nb_bits;            code_prefix = code >> (32 - table_nb_bits);            subtable_bits = n;            codes[i].bits = n;            codes[i].code = code << table_nb_bits;            for (k = i+1; k < nb_codes; k++) {                n = codes[k].bits - table_nb_bits;                if (n <= 0)                    break;                code = codes[k].code;                if (code >> (32 - table_nb_bits) != code_prefix)                    break;                codes[k].bits = n;                codes[k].code = code << table_nb_bits;                subtable_bits = FFMAX(subtable_bits, n);            }            subtable_bits = FFMIN(subtable_bits, table_nb_bits);            j = (flags & INIT_VLC_LE) ? bitswap_32(code_prefix) >> (32 - table_nb_bits) : code_prefix;            table[j][1] = -subtable_bits;            ff_dlog(NULL, "%4x: n=%d (subtable)\n",                    j, codes[i].bits + table_nb_bits);            index = build_table(vlc, subtable_bits, k-i, codes+i, flags);            if (index < 0)                return index;            /* note: realloc has been done, so reload tables */            table = (volatile VLC_TYPE (*)[2])&vlc->table[table_index];            table[j][0] = index; //code            i = k-1;        }    }     for (i = 0; i < table_size; i++) {        if (table[i][1] == 0) //bits            table[i][0] = -1; //codes    }     return table_index;}  /* Build VLC decoding tables suitable for use with get_vlc().    'nb_bits' sets the decoding table size (2^nb_bits) entries. The   bigger it is, the faster is the decoding. But it should not be too   big to save memory and L1 cache. '9' is a good compromise.    'nb_codes' : number of vlcs codes    'bits' : table which gives the size (in bits) of each vlc code.    'codes' : table which gives the bit pattern of of each vlc code.    'symbols' : table which gives the values to be returned from get_vlc().    'xxx_wrap' : give the number of bytes between each entry of the   'bits' or 'codes' tables.    'xxx_size' : gives the number of bytes of each entry of the 'bits'   or 'codes' tables. Currently 1,2 and 4 are supported.    'wrap' and 'size' make it possible to use any memory configuration and types   (byte/word/long) to store the 'bits', 'codes', and 'symbols' tables.    'use_static' should be set to 1 for tables, which should be freed   with av_free_static(), 0 if ff_free_vlc() will be used.*/int ff_init_vlc_sparse(VLC *vlc_arg, int nb_bits, int nb_codes,                       const void *bits, int bits_wrap, int bits_size,                       const void *codes, int codes_wrap, int codes_size,                       const void *symbols, int symbols_wrap, int symbols_size,                       int flags){    VLCcode *buf;    int i, j, ret;    VLCcode localbuf[1500]; // the maximum currently needed is 1296 by rv34    VLC localvlc, *vlc;     vlc = vlc_arg;    vlc->bits = nb_bits;    if (flags & INIT_VLC_USE_NEW_STATIC) {        av_assert0(nb_codes + 1 <= FF_ARRAY_ELEMS(localbuf));        buf = localbuf;        localvlc = *vlc_arg;        vlc = &localvlc;        vlc->table_size = 0;    } else {        vlc->table           = NULL;        vlc->table_allocated = 0;        vlc->table_size      = 0;         buf = av_malloc_array((nb_codes + 1), sizeof(VLCcode));        if (!buf)            return AVERROR(ENOMEM);    }      av_assert0(symbols_size <= 2 || !symbols);    j = 0;#define COPY(condition)\    for (i = 0; i < nb_codes; i++) {                                        \        GET_DATA(buf[j].bits, bits, i, bits_wrap, bits_size);               \        if (!(condition))                                                   \            continue;                                                       \        if (buf[j].bits > 3*nb_bits || buf[j].bits>32) {                    \            av_log(NULL, AV_LOG_ERROR, "Too long VLC (%d) in init_vlc\n", buf[j].bits);\            if (!(flags & INIT_VLC_USE_NEW_STATIC))                         \                av_free(buf);                                               \            return -1;                                                      \        }                                                                   \        GET_DATA(buf[j].code, codes, i, codes_wrap, codes_size);            \        if (buf[j].code >= (1LL<<buf[j].bits)) {                            \            av_log(NULL, AV_LOG_ERROR, "Invalid code %"PRIx32" for %d in "  \                   "init_vlc\n", buf[j].code, i);                           \            if (!(flags & INIT_VLC_USE_NEW_STATIC))                         \                av_free(buf);                                               \            return -1;                                                      \        }                                                                   \        if (flags & INIT_VLC_LE)                                            \            buf[j].code = bitswap_32(buf[j].code);                          \        else                                                                \            buf[j].code <<= 32 - buf[j].bits;                               \        if (symbols)                                                        \            GET_DATA(buf[j].symbol, symbols, i, symbols_wrap, symbols_size) \        else                                                                \            buf[j].symbol = i;                                              \        j++;                                                                \    }    COPY(buf[j].bits > nb_bits);    // qsort is the slowest part of init_vlc, and could probably be improved or avoided    AV_QSORT(buf, j, struct VLCcode, compare_vlcspec);    COPY(buf[j].bits && buf[j].bits <= nb_bits);    nb_codes = j;     ret = build_table(vlc, nb_bits, nb_codes, buf, flags);     if (flags & INIT_VLC_USE_NEW_STATIC) {        if(vlc->table_size != vlc->table_allocated)            av_log(NULL, AV_LOG_ERROR, "needed %d had %d\n", vlc->table_size, vlc->table_allocated);         av_assert0(ret >= 0);        *vlc_arg = *vlc;    } else {        av_free(buf);        if (ret < 0) {            av_freep(&vlc->table);            return ret;        }    }    return 0;}  void ff_free_vlc(VLC *vlc){    av_freep(&vlc->table);}